Our pool in upstate NY was shocked when it was opened in April. Since then I have tested regularly with the TF-100 kit, and all the numbers are basically good. PH 7.5, TA 100, CYA a little high @ 60, and FC 11. The FC might seem a little high, but I've been battling a high CYA, it was as high as 90. I did let the FC get below the target level briefly a couple of weeks ago as an experiment, but not lately.
Today I noticed a little algae in several places in the pool. Why is this? I thought algae wouldn't grow if the FC level was ok. Should I shock the pool?
My next ? is, how much FC is safe to swim in? Let's say I shock the pool to 20ppm FC, is it ok to swim in? Thanks much in advance.